Food Inc.

For more on Food Inc.:
http://www.foodincmovie.com/
(Check out the Study Guide in the Educational Materials and the Reading List.)

If you were intrigued by the movie Food, Inc. you might want to also watch Food Matters and Fast Food Nation.
http://www.imdb.com/title/tt1528734/
http://www.imdb.com/title/tt0460792/

Books:
Animal, Vegetable, Miracle by Barbara Kingsolver.
http://www.animalvegetablemiracle.com/